Method for coating the interiors of hollow bodies

ABSTRACT

Method and means for coating the interior cylindrical surface of objects such as metal cans for food, beverages and other substances which need protection against injurious reaction with or pollution from contact with the material of the can. Airless spray coating of such surfaces revolving at high speed by stationary spray nozzles external of the can. The nozzles project impinging airless sprays having desirable patterns through respective ends of open ended can cylinders into longitudinally elongated contact with the interior surface.

United States Patent Hog strom et a1.

[ Feb. 8, 1972 [54] METHOD FOR COATING THE INTERIORS OF HOLLOW BODIES[72] lnventors: Edwin F. Hogstrom, North Olmstead; W11- linm C.Stumphluzer, Shefl'ield Lake; Eric T. Nord, Oberlin, all of Ohio [7 3]Assignee: Nordson Corporation, Amherst, Ohio [22] Filed: Mar. 5, 1970[21] Appl, No.:' 16,733

[52] U.S.Cl. ..117/96, 117/97,117/101 1l7/105.4, 117/132 BE,117/132 C,117/161 R,

[51] Int. Cl. ..B44d I/08, 1305b 13/06 [58] FieldofSearch..1l7/95,96,97, 101, 104, 105.3, ll7/105.4, 161 R, 161 K; 118/55, 302,315, 316,

v 1 References Cited UNITED STATES PATENTS 2,848,819 8/1958 Schoenfeld..-1 17/97 X 3,081,947 3/ 1963 Walter ..1 18/317 X PrimaryExaminerAlfred 1.. Leavitt Assistant EXaminer-Edward G. WhitbyAttorney-Bosworth, Sessions, Herrstrom and Cain [57] ABSTRACT 21 Claims,9 Drawing Figures PA-IENIEnrEa 8 me 3,640,758

SHEET 1 BF 3 t a 7 r INVENTORS EDWIN E HOG$7ROM BY W/LL/AM c.STUMPHAUZER ER/C z NORD I ATTORNEYS k mzmsorw we 3640.758

SHEET 2 OF 3 INVENTORS EDW/N E HOGSTROM BY W/LL/AM C STUMPHfl/ZER ER/C7. IVORD flow/02%, 5%, mm am ATTORNEYS BACKGROUND OF THE INVENTION Thisinvention relates to methods and means for coating the interiors ofcylindrical objects such as metal cans and more particularly, toimproved methods and apparatus for applying a uniformcoating to theinterior surface of a cylindrical container while both ends are open.

Various methods have been proposed for coating the interiors of cansused to contain food, beverages and various liquids or gases to protectthe contents from contact with the can material. These methods and thecorresponding means have varied to some extent depending upon thecharacteristics of the can to be coated. The prior practices describedbelow and our own invention are directed particularly to coatingcircular cylindrical cans.

A commonly produced type of metal can is made in three pieces;Three-piece cans, so called, comprise open ended cylindrical body shellswith separate top and bottom end discs which may be coated separatelyand apart from the body shell. The interior of the cylindrical body isconventionally made of metal and has a seam running the length of thecan. This seam may be of any common type such as a lapped seam which issoldered and crimped or cemented, or a butt seam which is welded.

Spray coating the interior of the double open end can, or cylinder, hasgenerally been accomplished in the prior art by an air atomin'ng orairless spray nozzle mounted on a lance that is reciprocated into andout of the can along its axis which the can is rotated. In the lancingoperation the spray may be turned on either while the lance carrying thenoule is reciprocated from its innermost position to a position outsidethe can, while moving from an external position to the inside of thecan, 'or during reciprocation both into and out of the can.

Several difficulties are encountered with the use of the laneing method.The coating material tends to be applied to the wall of the can in ahelical path which often results in helical streaks along the can wall.Other problems occur in timing the spray with the movement of the lance.In particular, it is difficult to out 01f the flow of coating materialat the precise instant thatthe spray begins to be projected outside theopen end of the can as the lance emerges therefrom, and at the same timesupply a sufficiently thick coating to he can wall adjacent the openend. Overspray is always excessive and, consequently, maintenance of thereciprocating device and the related mechanism is required at frequentintervals. Finally, the lancing method is quite inefficient in thatconsiderable time is required to move the lance into the can and towithdraw it therefrom.

Another method of coating the interiors of double open end cans isillustrated in Eberhart U.S. Pat, No. 2,189,783. The Eberhartpatentteaches the employment of two air spray nozzles for alternatelyspraying the interior of a can while it is rotating. Each can to besprayed is indexed to a spraying station where it is rapidly rotated ina particular direction while a spray of liquid coating material isprojected against the interior surface through one open end. Excessspray which is blown through the can body is carried away by an exhaustpipe located adjacent the opposite end of the can. The excess spray isdrawn off into the exhaust pipe by an exhaust fan or blower. Theoverspray loss is wasteful and burdensome.

After several revolutions of the can the spray is automati cally cut Hand the can is conveyed to another spraying station where it is revolvedrapidly in the opposite direction. The interior of the can is sprayedwith the liquid coating material through the opposite end of the canwhile the can is revolved. The can is thus sprayed from opposite endsalternately while being revolved in opposite directions. The can is thenconveyed away from the last-spraying station and dropped onto aninclined discharge runway which carried it to a suitable place ofdisposal.

The method disclosed by Eberhart is inefficient in that two sprayingoperations are required to adequately coat the interior of the can.Moreover, the system of Eberhart as well as those described above isquite wasteful of coating material in permitting a high percentage ofoverspraying which not only results in wasted coating material but alsonecessitates the expenditure of a large amount of time for cleaning ofequipment.

SUMMARY OF THE INVENTION A general object of our invention is to providea method and apparatus for spraying the interiors of cylindrical canshaving both ends open which substantially eliminates the disadvantagesdescribed above encountered with prior can spraying methods andapparatus.

A particular object of our invention is to provide a method andapparatus for spraying the interiors of cans having two open ends thatis faster and more economical than prior practice, producessubstantially no overspray, and provides a desirable uniform filmthickness of coating material throughout the whole interior surface. Amore particular object is to provide a method and apparatus for sprayingthe interiors of double open end cans that employs two fixed airlessspray nozzles positioned at opposite ends of a rotating can, theoverlapping spray from the noales unifonnly coating the interior surfaceof the can.

In a preferred form our method includes the steps of rotating the can orother cylindrical object about its own axis and projecting atomizedairless spray patterns of liquid-coating material from fixed noules intothe rotating object through both open ends. Further steps comprisedirecting the sprayed material into angular longitudinally elongatedcontact with the interior of the object, distributing the materialdeposited from both spray patterns substantially uniformly throughoutthe length of the objects and restricting the spray from each nozzle tofall short of the open end of the object remote from the nozzle fromwhich the spray is projected. As a result the interior of the object iscoated unifomrly and overspray from the nozzles is substantially reducedcompared to prior methods.

A preferred form of apparatus for practicing our method includes meansfor rotating the object about its own axis, a first spray noulepositioned adjacent one open end of the object and a second spray nozzlepositioned adjacent the other open end of the object. The nozzles areoriented to spray coating material through opposite open ends of therotating object to angular longitudinally elongated contact with theinterior thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of apparatus forspraying the interiors of can bodies through both open ends according tothis invention.

FIG. 2 is a fragmentary side view of can rotating means suitable for usein this invention.

FIG. 3 is a plan view of a conventional drumhead" nozzle illustratingparticularly the nozzle orifice.

FIG. 4 is a plan view of a controlled distribution" nozzle illustratingparticularly the nozzle orifice.

FIG. 5 shows the distribution pattern of a conventional drumhead spraynozzle, preferred for use in this invention.

FIG. 6 shows the distribution pattern of a controlled distribution spraynozzle.

FIG. 7 is a plan view of two conventional drumhead nozzles spray coatingthe interior of a can in accordance with a preferred form of thisinvention.

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 7.

FIG. 9 is a plan view of two controlled distribution nozzles spraycoating the interior of a can in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A. Coating Apparatus and MethodGenerally The cans or other hollow bodies to be coated must be indexedone by one to a spraying station where they are I revolved rapidly to besprayed by stationary airless spray guns.

The cans, still rotating, are then dropped or stepped out of theindexing apparatus to an inclined belt or chute on which they continueto rotate and roll to a baking oven. The belt and/or chute is of such alength that the cans will roll for a sufficient time and sufficientrevolutions to allow the coating to become tacky enough so that it willno longer flow. The uniformity of coating obtained during spraying isthus not impaired before the coating is fixed by baking. The cans arethen moved into the oven where the coating is baked at a prescribedtemperature for a proper time.

Suitable can indexing and rotating apparatus for our purposes isdisclosed in US. Pat. No. 2,189,783 to Eberhart. The apparatus shownthere may be employed for indexing and rotating cans. Our method andapparatus for coating the interiors of cans requires, however, only onespraying station and one direction of rotation for the mos to be sprayedinstead of two stations where cans are rota in opposite directions astaught by Eberhart.

Preferably the spraying of the can interiors should result in a uniformfilm distribution with a weight of coating of a particular number ofmilligrams per square inch according to manufacturers specifications.Coating materials may be vinyl, epoxy, butoxy, phenalic, acrylic, alkyd,modifications of the above, or other suitable coatings.

Film distribution is commonly determined electrically by measuring theresistance of the film at a plurality of points on the interior surfaceof the can. Overspray may be ascertained by determining the weight gainof the can and .the weight of oversprayed material which is capturedduring the spraying process. Overspray is then calculated as apercentage of the weight of material sprayed on the can plus the weightof the captured overspray material.

In FIGS. 1 through 6 preferred forms of apparatus for coating theinteriors of hollow bodies such as cans is illustrated.

In FIG. 1 can indexing and rotating apparatus, generally designated A,is shown rotating a double open end can shell 10 at a spraying station Swhere two fixed, preferably like or similar, nozzles 12 and 13 arepositioned at opposite ends of the can to spray and coat the interiorthereof. The nozzles 12 and 13 are oriented with respect to the axis ofthe can, its direction of rotation and the intended line and angle ofcontact of the spray fan with the inside of the can to provide the veryrapid coating of uniform thickness discussed more fully below. Thenozzles l2, l3 and the automatic guns 12g and 13g therefor arerotatably, pivotally and adj ustably mounted on indexing tables 15, 15'respectively, that allow each nozzle to be positioned bodily and rotatedabout horizontal and vertical axes with respect to the interior of thecan to be coated.

Each can is rotated in a direction that advances the exposed edge of thelapped joint of the shell of the can foremost into a spray fan. Thenozzles may be oriented to direct a tangential component of the sprayfan at the leading edge-of the lapped joint. The can is rotated at highspeed, characteristically between 500 and 3,000 r.p.m., with a typicalexample being 1,800 r.p.m. The coating material is sprayed into theinterior of the can during a little more than 3 revolutions, e.g., forabout 100 to 200 milliseconds. A uniform coating of desired thickness,for example, 3.5 to 6.5 milligrams per square inch is deposited.Overspray is minimized by selecting and/or adjusting the angle ofincidence between the coating material and the interior surface of thecan to overlap the sprays and, preferably, to produce mutual impingementand interference between oppositely directed sprayed particles orstreams. The coating material must have properties of good wetabilityand adhesion, and viscosity is characteristically within a range of 14to 40 seconds as measured with a Zahn No. 2 efilux cup at 77 F. Thecoating is deliberately sprayed off the proximate edge of the can for adistance of, for example one-sixteenth inch to ensure full coatingthickness to and on the edge.

Immediately after each can is coated and while still rotating it isstepped to a releasing station generally indicated as 16, FIG. 1, whereit is released from the rotating and indexing apparatus and caused toroll down an inclined chute 18 to and/or into a baking oven 20. Bycausing the freshly coated can to continue to rotate for 30 to 60seconds at about 270 r.p.m.

- and/or roll down the chute 18 at the same rate for the same time thecoating material is prevented from accumulating in the can, and iscaused to set with uniform thickness before baking. The length of theinclined chute I8 is such that the can is caused to make a minimumnumber of setting revolutions, 50 for example, during which the paintbecomes tacky so that it will not flow, and volatiles have some chanceto escape the can before entering the baking oven. At the end of theinclined chute 18 the can may enter the oven 20 where the paint is bakedat a prescribed temperature; e.g., at 300 F. for about 6 minutes,sufficient to cure and harden the applied film of the particular coatingmaterial.

While we have mentioned our preference for particular speeds of rotationof typical cans while the coating spray is being applied, we also preferthat the can be rotated no less than a whole revolution, obviously, andalso that the can be rotated a whole number of revolutions plus afraction of a revolution corresponding to the circumferential distancethe can rotates while the flow from the nozzle builds up from zero tofull-flow, and vice versa, i.e., while the valve in the paint gun ismoving from closed to open, and vice versa. With a solenoid actuated,pneumatically operated valve the time taken for valve opening andclosing is small but finite, and long enough to permit the rapidlymoving coated surface to move an appreciable distance and be coveredwith a circumferential wedge of coating material of increasing depthwhile the valve is opening, and, desirably, should be covered with anequal and opposite wedge of decreasing depth while the valve is closing.Our teaching is essentially to efi'ect the overlap as fully aspracticable as examination of a few trial runs will suggest. It willalso occur to those skilled in the art that imperfection or omission ofthe overlap will diminish in importance as the number of paintingrevolutions and coatings increase beyond the first one.

FIG. 2 illustrates suitable means for rotating a can at the sprayingstation S in FIG. 1. As shown in FIG. 2 the cans to be sprayed are heldwithin a turret 21 which rotates incrementally about its axis to presentthe cans to the rotating means, generally designated R. The rotatingmeans includes a driven roller 22 supported by a bracket .23 secured toa frame. An idling roller 24 maintains the can in firm frictionalengagement with the driven roller. 7

Rotation of the driven roller is effected by a series of meshing gears22, 25 and 26 driven by a sprocket 27 which in turn is driven by a chain28. The chain meshes with a driving sprocket (not shown). Afterreceiving its coating each can is indexed to the releasing station 16and rolls down the chute 18 as described above. The can rotatingapparatus shown in FIG. 2 is illustrated and described in detail in theEberhart patent discussed above. Our invention, however, requires onlyone spraying station and one set of can-rotating apparatus instead ofthe two stations and sets of can-rotating apparatus required byEberhart.

A preferred form of spray nozzle for use in our invention is shown inFIG. 3 and is commonly known as a drumhead" nozzle. A common method ofgauging the distribution of flow from aparticular nozzle is to spray ashort burst of coating material against a vertical substrate with thespray pattern Characterisu'cally a particular nozzle will reflect itsown peculiar characteristics when gaged by the above described method. Adrumhead" nozzle, preferred for use in our method, has the spray patternF shown in FIG. 5, skewed heavily toward one end, in ideally, a 100-0percent flow distribution but, practically, in a substantially 95-5percent flow distribution. The maximum flow of coating material occursat a point 31 approximately 95 percent of the distance from one end ofthe fan and 5 percent form the other end. The amount of material flowingthe rest of the fan tapers substantially linearly from the point ofmaximum flow to points of minimum flow'at each end of the fan. i

The drumhead nozzle B shown in FIG. 3 has an orifice O that is widest atone end 32 to produce the point of maximum output 31 in the fan F andtapers to a narrowest point 33 corresponding to the point of minimumoutput in the spray fan.

Another form of nozzle which can effectively be used inour invention isthe controlled distribution nozzle, the spray pattern of which is shownin FIG. 6. As shown in FIG. 6, the maximum flow of coating materialoccurs at a point 31' approximately 75 percent from one end of the fan Fand 25 percent from the other end. The amount of material flowing in therest of the fan tapers substantially linearly from the point of maximumflow 31, to points of minimum flow at each end of the fan.

An illustrative form of orifice for a controlled distribution nozzle Bto give a 75-25 distribution pattern is shown in FIG. 4. This nozzle maycorrespond substantially to the familiar V- notch nozzle in which theorifice is slashed though a substantially hemispherical dome d with asingle cut to give a wellknown symmetrical pattern, except that theorifice 0' is a smooth merger of a long narrow cut from the left, asviewed, with a short wide cut from the right giving maximum width to theorifice at about 75-25 percent line k to produce the 75-25 spray patternshown in FIG. 6. This nozzle and a preferred way of making it isdisclosed andclaimed in application Ser. No. 13,598 filed Feb. 14, I970,assigned to the assignee of this application. B.'Coating Can Bodies withtwo Open Ends FIGS. 1, 7 and 8 illustrate diagrammatically the practiceof our invention with a pair of conventional drumhead nozzles Hand 13,having axes 12a and 13a, to coat the interiors of double open end can10. The nozzles are positioned similarly at opposite ends of the canand, to the same side of the axisof the can body, FIG. 7, and have theiraxes 12a and 13a inclined atan angle i, FIGS. 1 and 7, measuredhorizontally with respect to the vertical plane v through the axis ofthe can body. The nozzles are preferably inclined to direct the sprayfan F parallel to the horizontal plane h, FIG. 8, and are positioned adistance z from the plane of the can opening as shown in FIG. 7. Thehorizontal and vertical distances of the nozzles from the intersectionof planes h and v are represented by'x and y, respectively in FIG. 8.

The drumhead nozzles 12 and 13 are so positioned that the percent ornarrow portions N of the fans overlap and, preferably, impinge upon eachother over their entire width while the 95 percent or wide portions W ofthe fans areoverlapped by, for example, one inch and, preferably,impinge upon each other over that distance. The can is rotated in thedirection indicated by the arrow a, FIG.,8, so that the leading edge ofthe seam 34 is rotated directly into the spray fan F to be directly andcompletely coated thereby.

A beneficial etfect of the impinging sprays is the reduction andsubstantial elimination of overspray. Our tests and present observationssuggest that although the portion of the can beneath the overlapped partof the spray, FIG. 7, would apparently get more than its share of paint,such is not the actual result in terms of milligrams per square inchdeposited in the middle as compared with the deposit elsewhere in thecan. The nonoverlapping portions of the spray fans provide uniform,minimum, desired coatings on the flanges 35 and 36 of can 10 and producethe same uniform coating over the adjacent areas of the can interior.The tapered distribution parterns of the nozzles with the areas ofgreater output directed farther into the 'can compensate for thedifferent distances from each nozzle to the parts to be coated. Theresult is a uniform coating over all areas of the can interior.

We have found that under some conditions of paint wetability, viscosity,etc., and rapid rotation of the can while simul taneously sprayingimpinging spray fans into both ends of the can body, there tends to beproduced a coating of lesser thickness of the portion of the can beneaththe imping'ng portion of the fans. We presently suspect this to becaused by, possibly centrifugal force, possibly an excess of volatilesolvents momentarily confined in the material on and near the middle ofthe canand/or by the formation of a pressure wall in a center section ofthe can from which a surprising quantity of the coating particlesrebound.

The pressure wall" is presently believed or suspected to be builtup'from pressure injected in to the can interior by the impingingsprayfans, rapid release of solvents from the fans, and the rotation of thecan. We have found that the effect of the pressure wall can be overcomeby overlapping and impingingthe portions of the two fan sprays adjacenttheir points of maximum output 31 as described above so that a greatervolume of coating material is directed to the impinging areas.

Where the controlled distribution nozzles, FIG. 4, producing the patternshown in FIG. 6, are employed they should be positioned so that the 25percent or narrow portions N of the fans are aimed farthest'inwardly andcompletely overlap and, preferably, impinge upon each other while thewide or 75 percent portions W of the two spray patterns overlap and,preferably, impinge partially.

As shown in FIG. 9 the controlled distribution nozzles 12', 13 arepositioned with respect to the can to be coated essentially the same asthe drumhead nozzles with the 25 percent portion N of each pattern beingdirected farthest inwardly. The portions N of the two patterns impingeupon each other over their entire width while the portions W impingeover a part of their width. The nonimpinging areas of the portions Wprovide a uniform coating over the remainder of the can interior ofsubstantially the same thickness as that beneath the impinging areas ofthe sprays.

As with the drumhead nozzles, the greater volume of material in theimpinging portions of the fans appear to overcome thesuspected effect ofthe pressure wall. The controlled distribution nozzles, also, whenemployed in our method of coating the interiors of double open end cans,produce a substantially uniform coating over the can interior withsubstantially reduced overspray, regard also being had for sprayingconditions such as the wetability of the coating, its viscosity, etc.

Whether drumhead nozzles, controlled distribution nozzles orothernozzles are employed topractice our method we prefer that the twosprays be directed into aligned opposition and mutual impingement asdescribed above. The cans are coated satisfactorily however, if the twosprays are slightly misaligned so that they overlap but do not impinge.

For an example according to our method of spraying the double open endcan 10 with drumhead nozzles, they were positioned at an angle i of 52with respect to the plane v. The can 20 was about 2 11/16 inches indiameter and 4 13/16 inches long; The nozzles flowed 0.12 gal/minute ofwater at 500 p.s.i. In'this example the coating was sprayed at 750 psi.The distance. 2 from the nozzle to the plane of the can opening, FIG. 7,was about three-eighths inches. The distance x from the nozzle to theintersection of planes v and h was about 1.25 inches and the distance y,FIG. 8, was 0 inches. The can was rotated at 1,650 r.p.m. and the sprayfrom the nozzles was turned on for milliseconds. The coating materialwas a vinyl lacquer reduced to a viscosity of 20 seconds as measuredwith a Zahn No. 2 cup at 77 F. The material was heated to a temperatureof l35-l40 F. After spraying and coating the can was-released from itspainting station and continued to be rotated and rolledat about 272r.p.m. for 30-60 seconds before delivery to the baking oven. In the oventhe can was baked for about 6 minutes at a temperature of 300 F. Thebaked and cooled coating was uniform within a maximum variation of 1.25milligrams per square inch and overspray was within 4 percent.

For an example according to our method of spraying th double open endcan with controlled distribution nozzles 12 and 13", they werepositioned at an angle 1' of 55 with respect to the plane v. The can 10was about 2 1 H16 inches in diameter and 4 13/16 inches long. Thenozzles 12 and 13 flowed about 120 cc./minute of water at 40 psi. Inthis example the coating was sprayed at 750 p.s.i. The distance 2 fromthe nozzles to the plane of the can openings, FIGS. 7 and 9, was aboutthree-eighths inches. The distance x from the nozzle to the intersectionof planes v and h was about 1.25 inches and the distance y, FIG. 8, was0 inches. The can was rotated at 1,650 r.p.m. and the spray from thenozzles was turned on for 135 milliseconds. The can was then post rolledat 272 r.p.m. for 60 seconds. The coating material was a vinyl lacquerreduced to a viscosity of 22 seconds as measured with a Zahn No. 2 cupat 77 F. The reducing agent was a suitable solvent such as MIBK(methyl-isobutyl-ketone) and xylene. In the oven the can was baked forabout 6 minutes at a temperature of 300 F. The baked and cooled coatingwas uniform within a maximum variation of 1.25 milligrams per squareinch and overspray was less than 4 percent.

While we have specifically illustrated and described a preferred and analternate form of our invention, changes and improvements will occur tothose skilled in the art who come to understand its essential principlesand accomplishments. We do not therefore wish to be confined to thespecific forms of our invention herein specifically disclosed, nor inany other way inconsistent with the progress by which our invention haspromoted the art.

What we claim is:

l. The method of coating the interior surface of a cylindrical objecthaving open ends such as the shell of a beer can, comprising rotatingsaid object about its own axis, projecting atomized airless sprays ofliquid coating material from fixed nonles into said rotating objectthrough both said open ends, directing the sprayed material into angularlongitudinally elongated contact with the interior of said object,distributing the material deposited from both spray patternssubstantially uniformly throughout the length of the object, andrestricting the spray from each nozzle to fall short of the open end ofthe object remote from the nozzle from which the spray is projected.

2. The method of claim 1 with the step of projecting said spray whileremoving said object a fraction of a revolution more than an integralnumber of revolutions.

3. The method of claim 1 with the step of rotating said object at aspeed sufficient to provide centrifugal force upon the coating materialwhile the material is being projected upon said surface and while itisin a mobile state tending to aid in uniformity of distribution thereofthroughout said surface.

4. The method of claim 1 with the step of projecting said sprayssimultaneously.

5. The method of claim 1 with the step of projecting said sprays inaligned opposition and mutual impingement.

6. The method of claim 1 with the step of inclining said sprays to havea tangential component moving at the places of contact with said surfaceopposite the direction of movement of said surface.

7. The method of claim 6 with the step of projecting said sprayssimultaneously and into mutual opposition.

8. The method of claim 1 with the step of projecting said material forabout 3 revolutions of the object and depositing from about 4 to 9milligrams per square inch of material over said surface.

9. The method of claim 8 with the step of spraying said material duringa fraction of a revolution more than an inte al number of revolutions.

0. The method of claim 9 with the step of rotating said ob ject at aspeed sufficient to provide appreciable centrifugal force upon thecoating material, imposing said force upon the material as long as it isin a mobile state and inducing uniformity of distribution thereofthroughout said surface.

11. The method of claim 1 wherein the spray patterns are substantiallyfan shaped and are sprayed into substantially lineal contact with theinterior of said object.

12. The method of claim 11 with the step of inclining said fans to havea tangential movement at said line of contact moving opposite themovement of said surface.

13. The method of claim 11 with the step of spraying said materialduring the integral number of revolutions of said object plus a fractionof a revolution.

14. The method of claim 11 with the step of rotating said object at aspeed sufiicient to impose centrifugal force upon a coating materialwhile it is in a mobile state tending to aid in the uniformity ofdistribution thereof throughout said surface.

15. The method of claim 11 with the step of projecting said fanssimultaneously.

16. The method of claim 11 with the step of projecting said fans inaligned opposition and mutual impingement.

17. The method of claim 11 with the step of spraying said material forabout 3 revolutions of the object and depositing from about 4.5 to 6.5milligrams per square inch of material over said surface.

18. The method of claim 17 with the step of revolving said object afraction of a revolution more than an integral number of revolutions.

19. The method of claim 18 with the step of rotating said object at aspeed sufficient ti impose appreciable centrifugal force upon thecoating material while the material is in a mobile state tending to aidin the uniformity of distribution thereof throughout said surface.

20. The method of claim 19 with the step of projecting said fanssimultaneously.

21. The method of claim 20 with the step of projecting said fans inaligned opposition and mutual impingement.

UNITED STATES PATENT OFFICE Certifcate Patent No. 3,640,? 58 PatentedFebruary 8, 1972 Edwin F. Hogstrom, William C. Stumphauzer and Eric T.Nord Application having been made by Edwin F. Hogstrom, William C.Stumphauzer, and Eric T. Nord, the inventors named in the patent aboveidentified, and N ordson Corporation, Amherst, Ohio, a corporation ofOhio, the assignee, for the issuance of a certificate under theprovisions of Title 35, Section 256, of the United States Code, deletingthe names of William C. Stumphauzer and Eric T. Nord as joint inventors,and a showing and proof of facts satisfying the requirements of the saidsection having been submitted, it is this 19th day of February 197 4,certified that the names of said William C. Stumphauzer and Eric T. Nordare hereby deleted from the said patent as joint inventors with the saidEdwin F. Hogstrom.

FRED W. SHERLING Associate Solicitor.

P0-1050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTI'ON PatentNO- 3,640,7 58' Dated February 8, 1972 Inventor s Edwin F. H ogstrom,William C. Stumphauzer and Eric T. Nord It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 1, line 46, change "he can" to 1:he can.

Column 5, line 10 insert -inafter "flowing" Column 6, line 17, change"in' to" to --into- Claim 19, line 2, change "ti" to -to-.

Signed and sealed this 25th 'day of July 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR, ROBERT GOTTSCHALK Attestinp; Officer Commissionerof Patents

2. The method of claim 1 with the step of projecting said spray whileremoving said object a fraction of a revolution more than an integralnumber of revolutions.
 3. The method of claim 1 with the step ofrotating said object at a speed sufficient to provide centrifugal forceupon the coating material while the material is being projected uponsaid surface and while it is in a mobile state tending to aid inuniformity of distribution thereof throughout said surface.
 4. Themethod of claim 1 with the step of projecting said sprayssimultaneously.
 5. The method of claim 1 with the step of projectingsaid sprays in aligned opposition and mutual impingement.
 6. The methodof claim 1 with the step of inclining said sprays to have a tangentialcomponent moving at the places of contact with said surface opposite thedirection of movement of said surface.
 7. The method of claim 6 with thestep of projecting said sprays simultaneously and into mutualopposition.
 8. The method of claim 1 with the step of spraying saidmaterial for about 3 revolutions of the object and depositing from about4 to 9 milligrams per square inch of material over said surface.
 9. Themethod of claim 8 with the step of spraying said material during afraction of a revolution more than an integral number of revolutions.10. The method of claim 9 with the step of rotating said object at aspeed sufficient to provide appreciable centrifugal force upon thecoating material, imposing said force upon the material as long as it isin a mobile state and inducing uniformity of distribution thereofthroughout said surface.
 11. The method of claim 1 wherein the spraypatterns are substantially fan shaped and are sprayed into substantiallylineal contact with the interior of said object.
 12. The method of claim11 with the step of inclining said fans to have a tangential componentat said line of contact moving opposite the movement of said surface.13. The method of claim 11 with the step of spraying said materialduring an integral number of revolutions of said object plus a fractionof a revolution.
 14. The method of claim 11 with the step of rotatingsaid object at a speed sufficienT to impose centrifugal force upon thecoating material while it is in a mobile state tending to aid in theuniformity of distribution thereof throughout said surface.
 15. Themethod of claim 11 with the step of projecting said fans simultaneously.16. The method of claim 11 with the step of projecting said fans inaligned opposition and mutual impingement.
 17. The method of claim 11with the step of spraying said material for about 3 revolutions of theobject and depositing from about 4.5 to 6.5 milligrams per square inchof material over said surface.
 18. The method of claim 17 with the stepof revolving said object a fraction of a revolution more than anintegral number of revolutions.
 19. The method of claim 18 with the stepof rotating said object at a speed sufficient to impose appreciablecentrifugal force upon the coating material while the material is in amobile state tending to aid in the uniformity of distribution thereofthroughout said surface.
 20. The method of claim 19 with the step ofprojecting said fans simultaneously.
 21. The method of claim 20 with thestep of projecting said fans in aligned opposition and mutualimpingement.